The present invention relates to a container management apparatus and the like for managing a container that is an environment in which an application is executed.
DevOps is known as a program development method for the purpose of prompt implementation from development to provision of an application. For a technology supporting DevOps, containerization technology is widely used. The containerization technology is a technology for virtualizing an application layer, on a shared OS layer. According to the containerization technology, it is possible to deploy an application development and/or test environment more promptly with less overhead than VM (Virtual Machine), which virtualizes hardware and/or devices including OS. Typical container engine products for implementing the containerization technology include Docker® of Docker, Inc.
In a container built on a host computer, only differences from shared OS information are managed. If a container is deleted, data in the container is not maintained. To avoid this, Docker provides “data volume” as a function. A data volume is created on a host OS where Docker is running, the data volume is mounted to a container, and data is stored in the data volume from the container, whereby the data can be persisted. Such a data volume can also be created on a storage apparatus by using “plugin” provided by Docker, Inc.
In Docker, “Docker image” is required when a container is deployed. A Docker image is an image file in which information on an environment of a container required for deployment is collected. There are two types of Docker image, namely, Docker images provided by, for example, Docker, Inc. and Docker images created by users from existing containers. A Docker image is created by imaging a container of which environment is configured by a user. From that Docker image, multiple containers with similar environments can be instantly deployed. However, a Docker image does not include hardware information of a container. Accordingly, if a Docker image is created from a container to which a data volume is attached, the Docker image does not include information on the data volume, but only includes information on differences respect to an application from OS information of the container.
Moreover, recently, Oracle Corporation has begun distributing a Docker image for an environment of Oracle® DB, which is an example of RDBMS, and the use of RDBMS on a container is becoming widespread.
For example, among technologies related to containers, a technology for facilitating access to a file in a file system on a virtual file container instance is known (for example, see Japanese Patent Laid-Open No. 2017-76264).